1. Field of the Invention
The present invention relates to audio playback and, more particularly, to efficient playback rate adjustment on a portable media device.
2. Description of the Related Art
It is well known that previously recorded audio files can be played back on an audio device. Typically, the audio playback is done at the same rate that the media was recorded. However, in some situations, it is desirable to speed up the playback rate or slowdown the playback rate. For example, it may be helpful to a user of the audio device to speed up the playback rate when the user is scanning an audio recording of a previously attended meeting. On the other hand, if the user of the audio device has difficulty understanding the audio recording, the playback rate could be slowed. As an example, if the language of the audio being played back is not the native language of the user, slowing the playback rate can be helpful to the user.
Conventionally, there are various approaches that can be used to provide speed-up or slowdown of audio playback. These conventional approaches involve complicated algorithms, sometimes referred to as time-scaling algorithms. Many of these conventional approaches also undesirably lose the natural cadence associated with speech. These complicated algorithms analyze audio data to determine appropriate frames where time-splicing should occur and then perform the time-splicing of the frames. Other transformation-based analysis approaches offer the promise of high quality results, but are even more computationally intensive. Unfortunately, however, these algorithms consume or require substantial amounts of processing resources, including high performance computational units and substantial amounts of memory. However, with portable audio devices, such as hand-held audio players, processing resources are limited. Portable audio players are designed to be small, light-weight and battery powered. Hence, portable audio players are lower performance computing devices than are personal computers, such as desktop computers, which are high performance computing devices as compared to portable audio players. Consequently, the conventional algorithms are not well-suited for execution on portable media players.
Thus, there is a need for improved techniques to facilitate playback rate adjustment on portable media players.